Yes, done both 1. and 2. and same error encountered.
@distantnative pointed me to this issue: https://github.com/getkirby/kirby/issues/1861
thank you @texnixe Iâve been reading a lot of treads you wrote and now Iâm quite excited to meet you in person! 
I read the whole tread but I donât understand the solution⌠Can you help me? Thanks!
L
The main point is this post where @ahmetbora compared the headers of a normal request in the Panel vs. those from the installation where the error happened (an error that sounds a lot like what you are experiencing).
He found that instead of the HTTP_COOKIE header, one called HTTP_STORED_COOKIE was sent back. And thatâs why authentication with Kirby failed.
In the end it was a wrong setting on the side of the server host.
So great start would be, if you could get the request headers in the Panel from your installation - the request that fails (from which you see the error message you posted at the beginning of this thread). 
thanks @distantnative. How can I get request headers? It sounds like Itâs easier to change hosting! Anyway I agree, itâs a hosting problem.
You can see them in the network tab of your browser (in dev tools)
Thanks, Iâm not sure itâs exactly what you asked â Iâm not that PRO â find here first the normal page headers and then the headers after the error message.
Without error
Almost! If you now click on the system entry in that list, you will see the data of the actual request in a sidebar on the right
{âcodeâ:200,âdataâ:{âasciiâ:{"/\u00b0|\u2080/":â0â,"/\u00b9|\u2081/":â1â,"/\u00b2|\u2082/":â2â,"/\u00b3|\u2083/":â3â,"/\u2074|\u2084/":â4â,"/\u2075|\u2085/":â5â,"/\u2076|\u2086/":â6â,"/\u2077|\u2087/":â7â,"/\u2078|\u2088/":â8â,"/\u2079|\u2089/":â9â,"/\u00c0|\u00c1|\u00c2|\u00c3|\u00c5|\u01fa|\u0100|\u0102|\u0104|\u01cd|\u00c4|A/":âAâ,"/\u00e0|\u00e1|\u00e2|\u00e3|\u00e5|\u01fb|\u0101|\u0103|\u0105|\u01ce|\u00aa|\u00e6|\u01fd|\u00e4|a|\u0430/":âaâ,"/\u0411/":âBâ,"/\u0431/":âbâ,"/\u00c7|\u0106|\u0108|\u010a|\u010c|\u0426/":âCâ,"/\u00e7|\u0107|\u0109|\u010b|\u010d|\u0446/":âcâ,"/\u00d0|\u010e|\u0110/":âDjâ,"/\u00f0|\u010f|\u0111/":âdjâ,"/\u0414/":âDâ,"/\u0434/":âdâ,"/\u00c8|\u00c9|\u00ca|\u00cb|\u0112|\u0114|\u0116|\u0118|\u011a|\u0415|\u0401|\u042d/":âEâ,"/\u00e8|\u00e9|\u00ea|\u00eb|\u0113|\u0115|\u0117|\u0119|\u011b|\u0435|\u0451|\u044d/":âeâ,"/\u0424/":âFâ,"/\u0192|\u0444/":âfâ,"/\u011c|\u011e|\u0120|\u0122|\u0413/":âGâ,"/\u011d|\u011f|\u0121|\u0123|\u0433/":âgâ,"/\u0124|\u0126|\u0425/":âHâ,"/\u0125|\u0127|\u0445/":âhâ,"/\u00cc|\u00cd|\u00ce|\u00cf|\u0128|\u012a|\u012c|\u01cf|\u012e|\u0130|\u0418/":âIâ,"/\u00ec|\u00ed|\u00ee|\u00ef|\u0129|\u012b|\u012d|\u01d0|\u012f|\u0131|\u0438|i\u0307/":âiâ,"/\u0134|\u0419/":âJâ,"/\u0135|\u0439/":âjâ,"/\u0136|\u041a/":âKâ,"/\u0137|\u043a/":âkâ,"/\u0139|\u013b|\u013d|\u013f|\u0141|\u041b/":âLâ,"/\u013a|\u013c|\u013e|\u0140|\u0142|\u043b/":âlâ,"/\u041c/":âMâ,"/\u043c/":âmâ,"/\u00d1|\u0143|\u0145|\u0147|\u041d/":âNâ,"/\u00f1|\u0144|\u0146|\u0148|\u0149|\u043d/":ânâ,"/\u00d2|\u00d3|\u00d4|\u00d5|\u014c|\u014e|\u01d1|\u0150|\u01a0|\u00d8|\u01fe|\u00d6|O/":âOâ,"/\u00f2|\u00f3|\u00f4|\u00f5|\u014d|\u014f|\u01d2|\u0151|\u01a1|\u00f8|\u01ff|\u00ba|\u00f6|o|\u043e/":âoâ,"/\u041f/":âPâ,"/\u043f/":âpâ,"/\u0154|\u0156|\u0158|\u0420/":âRâ,"/\u0155|\u0157|\u0159|\u0440/":ârâ,"/\u015a|\u015c|\u015e|\u0218|\u0160|\u0421/":âSâ,"/\u015b|\u015d|\u015f|\u0219|\u0161|\u017f|\u0441/":âsâ,"/\u0162|\u021a|\u0164|\u0166|\u0422/":âTâ,"/\u0163|\u021b|\u0165|\u0167|\u0442/":âtâ,"/\u00d9|\u00da|\u00db|\u0168|\u016a|\u016c|\u016e|\u0170|\u0172|\u01af|\u01d3|\u01d5|\u01d7|\u01d9|\u01db|\u0423|\u00dc|U/":âUâ,"/\u00f9|\u00fa|\u00fb|\u0169|\u016b|\u016d|\u016f|\u0171|\u0173|\u01b0|\u01d4|\u01d6|\u01d8|\u01da|\u01dc|\u0443|\u00fc|u/":âuâ,"/\u0412/":âVâ,"/\u0432/":âvâ,"/\u00dd|\u0178|\u0176|\u042b/":âYâ,"/\u00fd|\u00ff|\u0177|\u044b/":âyâ,"/\u0174/":âWâ,"/\u0175/":âwâ,"/\u0179|\u017b|\u017d|\u0417/":âZâ,"/\u017a|\u017c|\u017e|\u0437/":âzâ,"/\u00c6|\u01fc/":âAEâ,"/\u00df/":âssâ,"/\u0132/":âIJâ,"/\u0133/":âijâ,"/\u0152/":âOEâ,"/\u0427/":âChâ,"/\u0447/":âchâ,"/\u042e/":âJuâ,"/\u044e/":âjuâ,"/\u042f/":âJaâ,"/\u044f/":âjaâ,"/\u0428/":âShâ,"/\u0448/":âshâ,"/\u0429/":âShchâ,"/\u0449/":âshchâ,"/\u0416/":âZhâ,"/\u0436/":âzhâ},âdefaultLanguageâ:âenâ,âisInstalledâ:true,âisLocalâ:false,âisOkâ:true,âkirbytextâ:true,âlanguagesâ:[{âcodeâ:âalâ,âdefaultâ:false,âdirectionâ:âltrâ,âlocaleâ:[""],ânameâ:âAlbanianâ,ârulesâ:[],âurlâ:âhttp://qendra-m.org/debug/al"},{âcodeâ:âenâ,âdefaultâ:true,âdirectionâ:âltrâ,âlocaleâ:[âenâ],ânameâ:âEnglishâ,ârulesâ:[],âurlâ:âhttp://qendra-m.org/debug/enâ}],âlicenseâ:false,âmultilangâ:true,ârequirementsâ:{âaccountsâ:true,âcontentâ:true,âcurlâ:true,âsessionsâ:true,âmbstringâ:true,âmediaâ:true,âphpâ:true,âserverâ:true},âsiteâ:âSiteâ,âslugsâ:[],âtitleâ:"Qendra Marr\u00ebdh\u00ebnieâ,âtranslationâ:{âauthorâ:âKirby Teamâ,âdataâ:{âaddâ:âAddâ,âavatarâ:âProfile pictureâ,âbackâ:âBackâ,âcancelâ:âCancelâ,âchangeâ:âChangeâ,âcloseâ:âCloseâ,âconfirmâ:âOkâ,âcopyâ:âCopyâ,âcreateâ:âCreateâ,âdateâ:âDateâ,âdate.selectâ:âSelect a dateâ,âdayâ:âDayâ,âdays.friâ:âFriâ,âdays.monâ:âMonâ,âdays.satâ:âSatâ,âdays.sunâ:âSunâ,âdays.thuâ:âThuâ,âdays.tueâ:âTueâ,âdays.wedâ:âWedâ,âdeleteâ:âDeleteâ,âdimensionsâ:âDimensionsâ,âdisabledâ:âDisabledâ,âdiscardâ:âDiscardâ,âdownloadâ:âDownloadâ,âduplicateâ:âDuplicateâ,âeditâ:âEditâ,âdialog.files.emptyâ:âNo files to selectâ,âdialog.pages.emptyâ:âNo pages to selectâ,âdialog.users.emptyâ:âNo users to select",âemailâ:âEmailâ,âemail.placeholderâ:"mail@example.comâ,âerror.access.loginâ:âInvalid loginâ,âerror.access.panelâ:âYou are not allowed to access the panelâ,âerror.access.viewâ:âYou are not allowed to access this part of the panelâ,âerror.avatar.create.failâ:âThe profile picture could not be uploadedâ,âerror.avatar.delete.failâ:âThe profile picture could not be deletedâ,âerror.avatar.dimensions.invalidâ:âPlease keep the width and height of the profile picture under 3000 pixelsâ,âerror.avatar.mime.forbiddenâ:âThe profile picture must be JPEG or PNG filesâ,âerror.blueprint.notFoundâ:âThe blueprint â{name}â could not be loadedâ,âerror.email.preset.notFoundâ:âThe email preset â{name}â cannot be foundâ,âerror.field.converter.invalidâ:âInvalid converter â{converter}ââ,âerror.file.changeName.emptyâ:âThe name must not be emptyâ,âerror.file.changeName.permissionâ:âYou are not allowed to change the name of â{filename}ââ,âerror.file.duplicateâ:âA file with the name â{filename}â already existsâ,âerror.file.extension.forbiddenâ:âThe extension â{extension}â is not allowedâ,âerror.file.extension.missingâ:âThe extensions for â{filename}â is missingâ,âerror.file.maxheightâ:âThe height of the image must not exceed {height} pixelsâ,âerror.file.maxsizeâ:âThe file is too largeâ,âerror.file.maxwidthâ:âThe width of the image must not exceed {width} pixelsâ,âerror.file.mime.differsâ:âThe uploaded file must be of the same mime type â{mime}ââ,âerror.file.mime.forbiddenâ:âThe media type â{mime}â is not allowedâ,âerror.file.mime.invalidâ:âInvalid mime type: {mime}â,âerror.file.mime.missingâ:âThe media type for â{filename}â cannot be detectedâ,âerror.file.minheightâ:âThe height of the image must be at least {height} pixelsâ,âerror.file.minsizeâ:âThe file is too smallâ,âerror.file.minwidthâ:âThe width of the image must be at least {width} pixelsâ,âerror.file.name.missingâ:âThe filename must not be emptyâ,âerror.file.notFoundâ:âThe file â{filename}â cannot be foundâ,âerror.file.orientationâ:âThe orientation of the image must be â{orientation}ââ,âerror.file.type.forbiddenâ:âYou are not allowed to upload {type} filesâ,âerror.file.undefinedâ:âThe file cannot be foundâ,âerror.form.incompleteâ:âPlease fix all form errors\u2026â,âerror.form.notSavedâ:âThe form could not be savedâ,âerror.language.codeâ:âPlease enter a valid code for the languageâ,âerror.language.duplicateâ:âThe language already existsâ,âerror.language.nameâ:âPlease enter a valid name for the languageâ,âerror.license.formatâ:âPlease enter a valid license keyâ,âerror.license.emailâ:âPlease enter a valid email addressâ,âerror.license.verificationâ:âThe license could not be verifiedâ,âerror.page.changeSlug.permissionâ:âYou are not allowed to change the URL appendix for â{slug}ââ,âerror.page.changeStatus.incompleteâ:âThe page has errors and cannot be publishedâ,âerror.page.changeStatus.permissionâ:âThe status for this page cannot be changedâ,âerror.page.changeStatus.toDraft.invalidâ:âThe page â{slug}â cannot be converted to a draftâ,âerror.page.changeTemplate.invalidâ:âThe template for the page â{slug}â cannot be changedâ,âerror.page.changeTemplate.permissionâ:âYou are not allowed to change the template for â{slug}ââ,âerror.page.changeTitle.emptyâ:âThe title must not be emptyâ,âerror.page.changeTitle.permissionâ:âYou are not allowed to change the title for â{slug}ââ,âerror.page.create.permissionâ:âYou are not allowed to create â{slug}ââ,âerror.page.deleteâ:âThe page â{slug}â cannot be deletedâ,âerror.page.delete.confirmâ:âPlease enter the page title to confirmâ,âerror.page.delete.hasChildrenâ:âThe page has subpages and cannot be deletedâ,âerror.page.delete.permissionâ:âYou are not allowed to delete â{slug}ââ,âerror.page.draft.duplicateâ:âA page draft with the URL appendix â{slug}â already existsâ,âerror.page.duplicateâ:âA page with the URL appendix â{slug}â already existsâ,âerror.page.duplicate.permissionâ:âYou are not allowed to duplicate â{slug}ââ,âerror.page.notFoundâ:âThe page â{slug}â cannot be foundâ,âerror.page.num.invalidâ:âPlease enter a valid sorting number. Numbers must not be negative.â,âerror.page.slug.invalidâ:âPlease enter a valid URL prefixâ,âerror.page.sort.permissionâ:âThe page â{slug}â cannot be sortedâ,âerror.page.status.invalidâ:âPlease set a valid page statusâ,âerror.page.undefinedâ:âThe page cannot be foundâ,âerror.page.update.permissionâ:âYou are not allowed to update â{slug}ââ,âerror.section.files.max.pluralâ:âYou must not add more than {max} files to the â{section}â sectionâ,âerror.section.files.max.singularâ:"You must not add more than one file to the â{section}â
What we need to see is the headers, the stuff you see on the right hand side when you click on an entry in the network tab list:
Request Method: GET
Status Code: 200 OK
Remote Address: 160.153.137.210:80
Referrer Policy: no-referrer-when-downgrade
Accept-Ranges: none
Age: 0
Content-Encoding: gzip
Content-Length: 6453
Content-Type: application/json; charset=UTF-8
Date: Wed, 10 Jun 2020 21:15:33 GMT
Vary: Accept-Encoding, User-Agent
X-Backend: all_requests
X-Cache: uncached
X-Cache-Hit: MISS
X-Cacheable: YES:Forced
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Accept: /
Accept-Encoding: gzip, deflate
Accept-Language: it-IT,it;q=0.9,en-US;q=0.8,en;q=0.7
Connection: keep-alive
content-type: application/json
Cookie: kirby_session=b9d93b3d06de7cbc93eae7e1d2468e9de8591cb0%2B1591830824.455b1c0292bcde12dcf1.593e3feb92f0d466454d462da5d84679c164a75d0d3e262677e2cad59a424d39
Host: qendra-m.org
Referer: http://qendra-m.org/debug/panel/login
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36
x-csrf: 9e04674429dd264cd3636883a3c1c170e04590e8d58ebbcf473044864dd3853d
x-requested-with: xmlhttprequest
view: panel
Is that from the request that fails? I think this is a problem with your hosting provider. Have you been in contact with them? Can you switch to another provider?
I agree! Itâs what I thought. I think itâs better to change hosting! Goddaddy is not Kirby friendly.