First "ERR_SPDY_PROTOCOL_ERROR" and then "Error establishing a database connection"

Hi,

The 5th of July the following error code was visible when browsing Google Chrome: ERRSPDYPROTOCOL_ERROR. When I went to Safari and tried
it displayed this error code: kcferrordomaincfnetwork 303

I have also tried to investigate in Chrome events for debugging. (Don’t now what to do with it though):

119628: URL_REQUEST
https://www.allduplo.se/
Start Time: 2018-07-17 14:36:04.632

t=6143 [st= 0] +REQUESTALIVE [dt=956] –> priority = “HIGHEST” –> url = “https://www.allduplo.se/” t=6144 [st= 1] URLREQUESTDELEGATE [dt=0] t=6144 [st= 1] +URLREQUESTSTARTJOB [dt=953]
–> loadflags = 18433 (MAINFRAMEDEPRECATED | MAYBEUSERGESTURE | VALIDATECACHE)
–> method = “GET”
–> url = “https://www.allduplo.se/”
t=6144 [st= 1] URLREQUESTDELEGATE [dt=0]
t=6144 [st= 1] HTTPCACHEGETBACKEND [dt=0] t=6144 [st= 1] HTTPCACHEOPENENTRY [dt=0]
–> neterror = -2 (ERRFAILED)
t=6144 [st= 1] HTTPCACHECREATEENTRY [dt=0] t=6144 [st= 1] HTTPCACHEADDTOENTRY [dt=0] t=6144 [st= 1] +HTTPSTREAMREQUEST [dt=1] t=6144 [st= 1] HTTPSTREAMJOBCONTROLLERBOUND –> sourcedependency = 119630 (HTTPSTREAMJOBCONTROLLER) t=6145 [st= 2] HTTPSTREAMREQUESTBOUNDTOJOB
–> sourcedependency = 119631 (HTTPSTREAMJOB) t=6145 [st= 2] -HTTPSTREAMREQUEST t=6145 [st= 2] +HTTPTRANSACTIONSENDREQUEST [dt=0]
t=6145 [st= 2] HTTPTRANSACTIONHTTP2SENDREQUEST_HEADERS
–> :authority: www.allduplo.se
:method: GET
:path: /
:scheme: https
accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,/;q=0.8
accept-encoding: gzip, deflate, br
accept-language: sv-SE,sv;q=0.9,en-US;q=0.8,en;q=0.7
cache-control: max-age=0
cookie: _ga=GA1.2.152687942.1531808727; gid=GA1.2.1796538786.1531808727 upgrade-insecure-requests: 1 user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10126) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36 t=6145 [st= 2] -HTTPTRANSACTIONSENDREQUEST
t=6145 [st= 2] +HTTPTRANSACTIONREADHEADERS [dt=951] t=7096 [st=953] HTTPTRANSACTIONREADRESPONSEHEADERS –> HTTP/1.1 200 status: 200 server: nginx date: Tue, 17 Jul 2018 12:36:03 GMT content-type: text/html; charset=UTF-8 vary: Accept-Encoding x-frame-options: SAMEORIGIN link: https://www.allduplo.se/wp-json/ 1; rel=“https://api.w.org/” link: https://www.allduplo.se/; rel=shortlink x-powered-by: EasyEngine 3.7.4 rt-fastcgi-cache: MISS content-encoding: gzip t=7096 [st=953] -HTTPTRANSACTIONREADHEADERS
t=7096 [st=953] +HTTPCACHEWRITEINFO [dt=1] t=7097 [st=954] HTTP2STREAMERROR –> description = “Server reset stream.” –> neterror = “ERRSPDYPROTOCOLERROR” –> streamid = 3
t=7097 [st=954] -HTTPCACHEWRITEINFO t=7097 [st=954] HTTPCACHEWRITEDATA [dt=0]
t=7097 [st=954] HTTPCACHEWRITEINFO [dt=0] t=7097 [st=954] URLREQUESTDELEGATE [dt=0] t=7097 [st=954] URLREQUESTFILTERSSET
–> filters = “GZIP”
t=7097 [st=954] -URLREQUESTSTARTJOB t=7097 [st=954] +URLREQUESTDELEGATE [dt=1] t=7097 [st=954] DELEGATEINFO [dt=1]
–> delegateblockedby = “MojoAsyncResourceHandler”
t=7098 [st=955] -URLREQUESTDELEGATE
t=7098 [st=955] HTTPTRANSACTIONREADBODY [dt=0] –> neterror = -337 (ERRSPDYPROTOCOLERROR) t=7098 [st=955] FAILED –> neterror = -337 (ERRSPDYPROTOCOLERROR) t=7099 [st=956] -REQUESTALIVE
–> neterror = -337 (ERRSPDYPROTOCOLERROR)

I tried to reboot the server in Linode but ended then up with "Error establishing a database connection".

Can somebody see whats wrong?

Thanks!